Mojave Desert ecosystem

As we close in on our winter season at the Desert Tortoise Conservation Center, located in Las Vegas, Nevada, it’s a great time to reflect on some of the highlights of our busy summer. One new program we offered to local teachers through the Clark County School District was a desert tortoise education workshop. This past June and July, a total of 32 teachers took part in the workshops. We’re happy to report that the classes were well received, and the response has been very positive!

Although rarely seen in the wild, the desert tortoise is the state reptile of Nevada and an important keystone species of the Mojave Desert ecosystem. Getting kids excited about science and math can be a huge hurdle for many teachers, and this was one of our main motivations for developing the desert tortoise workshop. One of the goals of the workshop was to provide teachers with curriculum that spotlights the cool adaptations of the desert tortoise while focusing on the important roles it plays in the Mojave Desert. With a focus on biology, ecology, and conservation, teacher participants were provided with fun and interactive desert tortoise curriculum, which also fulfills the Nevada classroom standards in life and earth sciences.

Throughout the workshop, teachers became students and were able to participate in hands-on activities and demonstrations to simulate current research projects being conducted by San Diego Zoo scientists. For example, teachers participated in a telemetry demonstration, learning hands-on how researchers use telemetry to study tortoise behavior following a release back into the wild. As a part of the activity, participants used radio tracking-equipment to “track” a model tortoise (made of Styrofoam), which had been affixed with a radio transmitter and hidden under vegetation. It was fun to watch a group of educators weave their way through the desert in unison, following the sound of a radio receiver, which released a “ping” as the Styrofoam tortoise grew closer.

Educators who participated in the workshop earned one credit toward professional development education through the Clark County School District, and were provided with desert tortoise resource materials and activities, which can be adapted to their individual grade levels. After a successful first run, we will be offering the workshop again to local teachers in February 2013. We’re excited to provide educators with the opportunity to study the desert tortoise and return to the classroom with a range of tools to promote continued education of this amazing animal and the Mojave Desert ecosystem.
Lori Scott is a research associate at San Diego Zoo Global’s Desert Tortoise Conservation Center. Read her previous post, Desert Tortoises Pose for Photos.

The desert soil is alive! Well, the soil itself isn’t really living, but life occurs throughout the soil of the Mojave Desert, so it’s important to always stay on designated trails and roads when you are in the desert.

Small microorganisms called cyanobacteria, which are from the same family as blue-green algae, actually live on the surface of bare soil in the desert. For most of the Mojave Desert, the soil is usually characterized by rough dark patches as shown in the photo, but these cyanobacteria, with the aid of different types of lichens, mosses, and other colonies of microorganisms, can sometimes produce colorful soil crusts. In both cases, the soils are called cryptobiotic crust.

Lichen covers cryptobiotic soil in the Mojave Desert.

Cryptobiotic crust is very important to the health of the desert—a great sign that barren land is actually growing and thriving. In fact, cryptobiotic crust helps produce nutrients and organic material that are recycled back into the soil, and this supports vegetation in the desert. This is great news for all the desert animals, like desert tortoises, that feast on plants as their main source of nutrition. The organic structure of cryptobiotic soil can also help native seeds to germinate (sprout), again an important feature for plant eaters like desert tortoises.

It takes a very long time for cryptobiotic soil to form, and it is also very sensitive to changes in its environment, so when it is disturbed, it does not have an easy time recovering. Some estimates indicate that it takes 250 years for damaged desert habitat to recover! When people use the desert for recreation, they have the opportunity to see and experience some of the most amazing scenery in the world. But if they are not careful, or they purposefully hike or drive off designated trails, cryptobiotic soil can be devastated.

When you step on cryptobiotic soil or drive over it, you kill millions of organisms that support the plant life that desert tortoises eat. If the soil is destroyed, then plants cannot grow, and tortoises will have nothing to eat. So if you know anyone who drives or hikes off trail and they tell you it’s okay because they are always careful not to run over tortoises or their burrows, you can now tell them it’s not okay because they are destroying cryptobiotic soils that allow plants to grow to feed the tortoises that they are being so careful to avoid!

As you can see, cryptobiotic soil is very important to the Mojave Desert ecosystem, and we should make every effort to avoid walking on or touching the soil. The next time you are out on a desert hike or driving down an old desert road, please stay on the designated routes to avoid harming the living soil below you.

The Desert Tortoise Conservation Center (DTCC) is located in southwest Las Vegas on a lovely patch of bajada (a broad sloping area of the desert surrounded by mountains). Here in the heart of the Mojave Desert, we are home to many desert tortoises, which are considered a flagship species in this ecosystem. That means the tortoise is an important representative of the Mojave Desert, and conservation and education efforts that relate to this species will benefit the entire ecosystem. The desert tortoise is the only chelonian (turtle/tortoise) in our area of the Southwest, but the Mojave is also home to a great many plant and animal species, including approximately 40 lizard and snake species, many of which use desert tortoise burrows as protection from predators and harsh environmental conditions. As a result of this relationship, many of these animals are found naturally right here at the DTCC.

Desert horned lizard

Some reptile species that we see regularly include the desert horned lizard Phrynosoma platyrhinos. These lizards are incredibly cute! Luckily, they are also very well adapted to desert life. When frightened, they stay very still and often resemble rocks, so be careful to watch out for one when driving down desert roads, and remember to slow down because they are incredibly hard to see. The desert horned lizard, like all horned lizards, eats ants. Like some other reptiles, they can be very difficult to care for properly in captivity, but they continue to be popular as pets because they are so cute. But these animals belong in the desert, and that’s the only place they can truly thrive, so remember: wildlife should never be removed from the wild. Every individual that is taken into captivity as a cute little pet is one less individual that is available to support native populations. Once an individual is removed from the desert, it is considered biologically dead, since it is no longer breeding and filling its natural role in the wild.

Another amazing lizard we find on site is the long-nosed leopard lizard Gambelia wislizenii, pictured above. These beautiful lizards are fairly fast and quite good hunters. They survive by eating insects, spiders, other lizards, snakes, rodents, and occasionally plant matter. They often use a sit-and-wait style of hunting, but are capable of becoming bipedal (standing on two legs) when they run fast. The amazing colors seen on the female pictured here are typical during the spring breeding season; however, at other times of the year leopard lizards lose the orange coloration.

Mojave green rattlesnake

In terms of venomous snakes, we are incredibly fortunate here in the Mojave because we have just a few species. Our most dangerous venomous snakes are rattlesnakes, which look very different from Colubrids (mildly or non-venomous species that kill their prey by constriction). The Mojave green rattlesnake Crotalus scutulatus and sidewinder Crotalus cerastes are two species of rattlesnake we have seen regularly at the DTCC. Like all rattlesnakes, they do not lay eggs but give birth to live young! The sidewinder is very small and often nocturnal, while the Mojave green is considerably larger and can be found during the day or night if environmental conditions allow. The rattlesnakes offer no threat to the tortoises and at times can be found taking shelter in their burrows!

In addition to these snakes, the Mojave Desert supports three species of rear-fanged venomous snakes: the lyre snake Trimorphodon biscutatus, the night snake Hypsiglena torquata, and the southwestern black-headed snake Tantilla hobartsmithi. All snakes should be treated with respect, as should all wildlife, so it is best not to approach them. Humans have experienced adverse reactions to their bites, but no deaths have been reported.

These animals, and many others, are found right here at the DTCC and in the surrounding desert. The Mojave is truly an amazing place, with a subtle and quiet beauty that is often overlooked. Apart from being a spectacular desert of incredibly extreme conditions, it is also rich with highly specialized plants and animals. Saving the desert tortoise is not just about protecting the tortoise; it also preserves the habitat in which the tortoise lives, thereby protecting many other plants and animals from the threat of extinction. If we lose our desert tortoises, we will lose the Mojave Desert ecosystem as well, so thanks to all of you who support our efforts!